Sometimes I've pondered a timeline right after Iliana's death where some of the bureaucrats/contenders got clever and just declared Iliana Empress forever. Leading to the ponies electing leaders to serve in her honor and memory. (Would probably lead to a city where Iliana's treated as a patron saint/near deity.) The Empire would probably still shrink, but some clever leaders could keep it from collapsing entirely.

Running a campaign that covers the fall of the Empire, where in Illiana's final days, she starts to cleanse all the evils she let live up to this point, in addition to searching out one last chance to become a Goddess. Its been a ton of fun.

Personally I think a travel travel campaign would be fun, where players can explore different timelines and see how their decisions or actions often very much matter... as do the decisions or actions of those they meet.